47 farmall M...carb wont adjust

Hey gang!
Here's where we're at!

I removed the inline filter and valve and added the sediment bowl/valve too the bottom of the tank, made sure the original steel line was in good shape and replaced the fitting in the carb with the screen filter. Now have great fuel flow!

Took the carb back apart and cleaned and recleaned....found the small idle jet in the neck of the carb partially clogged with paint. Got that cleaned out and the spray was a lot better.

Fired it up and she ran a lot better but still not great.

Used the propane torch trick around all the obvious areas for a vacuum leak...nothing. No change.

Pulled the carb back down...(no. 4th time) and went all thru it again.....still found nothing....put it back together and fired her back up......ran a LOT better.....running now with choke full open and taking fuel great!.
sounds good.

Took it for a spin down the old dirt road...running good but a little off......so I got back.....grabbed a wrench....loosened up the distributor and with a 1/8" turn....found her sweet spot and tightened her down.

Took another ride down the road....smooooooth.
Throttle response is now instant. Running perfect. Cap on exhaust isnt jumping around.....holds very steady.

Problem!!!......even though its running great....the carb adjuster screws still arent doing anything!. You can screw the main in and cut the fuel down and notice a change.....but I backed it out from closed 1-1/2 turns.....started it and I cant turn it out even more with no change. Is this normal?????

The only thing I havent checked...(and dont know how)....is the synchronization from the governor too the carb....but the governor seems too be working correctly.....let out on clutch in gear...motor falls slightly before governor kicks in.

Any more ideas or leave it alone and enjoy it?

Check the tips of the screws and see if they are worn. Or, if they have a wear ring around the tips. It also could be that the seats are shot. Either way, they are suppose to make the engine respond.

With the engine at a slow idle, you can screw with that bottom adjustment all day long and you will NOT notice any difference unless you screw it ALL the way in, which will stop the flow of fuel completely. The engine must be running wide open, under a load, before that bottom screw will make any difference. My advice is to screw it all the way in until it seats, and then turn it 3 full turns out (factory initial setting) and leave it there. The low speed idle adjustment, the one up on top, SHOULD make a big difference with the engine at a SLOW idle. The initial setting for that screw is 1 1/2 turns out.

Yes the bottom main jet adjustment you will only hear a difference at hi-idle under a slight load, this is when fuel is passing thru this jet. At idle it passes thru the idle jet.
There are more than one circuit in a carb.

1. Idle Circuit
2. Hi-speed Circuit
3. Choke Circuit
4. Vacum Circuit

Some have an accelerator circuit also (mainly on the older model automobiles) w/o fuel injection.

Get your idle circuit set then set your idle rpms then go to the highspeed circuit. Make sure your choke is open while making these adjustments. IF your timing is somewhat late or not advancing it can cause spitting and sputtering upon take off or acceleration and most people think it is a carb problem when it really isn't.

Hope this helps.
John